The objectives of this project are to continue and to expand research on the mapping of C- and G-banded human chromosomes through measurements of relative band positions. Measurements will be carried out on densitometric tracings of banded chromosomes. Bands will be analyzed on single- and multiple-line scannings obtained with a programmable scanning photometer. Densitometric data will be statistically analyzed by an especially programmed computer to give mean relative values of bands from any chromosome arm. C- and G-banded chromosomes will be obtained through denaturation-saline incubation procedures and proteolytic enzymes in order to study densitometrically both banding patterns produced. Data gathered will be used to localize and map relative band positions along the chromosome arms of each pair of the human normal complement. We will compare these data with the Paris Nomenclature and standardize chromosome landmarks in terms of their relative positions. This new mapping methodology would be most useful in describing all kinds of banding patterns and in detecting precisely new pathological conditions.